The research described in this application is designed to investigate the neurotransmitters responsible for the state- dependent synaptic control of trigeminal motoneuron membrane potential activity that is exerted by the pontine reticular formation during sleep and wakefulness. The proposed studies are organized within the framework of a paradoxical phenomenon known as "reticular response-reversal", whereby identical stimulation of a specific pontine reticular nucleus (pontis oralis) elicits excitatory postsynaptic potentials in trigeminal motoneurons during wakefulness and quiet sleep, and inhibitory postsynaptic potentials during active sleep. Combined microiontophoretic and intracellular recording studies are proposed to investigate the neurotransmitters which mediate these postsynaptic potentials during sleep and wakefulness. Accordingly, selective antagonists of putative inhibitory and excitatory neurotransmitters will be microiontophoretically applied next to the recorded somata of trigeminal motoneurons. The postsynaptic membrane responses induced by stimulation of the pontine reticular formation will then be analyzed during the states of wakefulness, quiet sleep, the non-rapid eye movement periods of active sleep and the rapid eye movement periods of active sleep. The proposed studies will (1) provide a comprehensive description and quantitative analysis of the individual waveform parameters of excitatory and inhibitory postsynaptic potentials recorded from trigeminal motoneurons in response to electrical stimulation of the pontine reticular formation during sleep and wakefulness, and (2) generate a normative fund of information relating to the excitatory and inhibitory neurotransmitters which mediate the reticular control of brainstem motoneurons during different behavioral states in the chronic unanesthetized, normally respiring cat. A pharmacological analysis of these diametrically opposed synaptic drives which act exclusively during specific behavioral states should provide important new insights into the normal functioning of state-regulated patterns of motor control.